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PatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

First-order sympathetic fibres originate in the hypothalamus and descend through the brainstem to level C8-T2 of the spinal cord where they synapse on preganglionic sympathetic nerve fibres.

Second-order fibres leave the cord at level T1 and ascend in the sympathetic chain over the apex of the lung to synapse in the superior cervical ganglion at the level of the bifurcation of the common carotid artery (C3-C4).

Third-order (postganglionic) fibres pass alongside the internal carotid artery, sending branches to the blood vessels and sweat glands of the face, and pass via the cavernous sinus to enter the eye via the superior orbital fissure. They pass via the long ciliary nerves to supply the iris dilator and Müller's muscle.

Heterochromia irides may occur with congenital Horner's syndrome.[5] The iris on the affected side remains blue whilst the other changes to brown. Pigmentation of the iris is under sympathetic control and is usually complete by the age of 2 years.

Horner's syndrome associated with pain always needs investigation. If there is arm, shoulder or hand pain think of Pancoast's syndrome. If pain is in the face or neck, think of carotid dissection. Pain and transient visual loss may be due to carotid dissection.[2]

In children, unless there is a known aetiology such as birth trauma, acquired Horner's syndrome requires thorough investigation; there is frequently a serious underlying cause, including neuroblastoma, trauma, rhabdomyosarcoma and brainstem vascular malformation.[7]

A rare congenital form of Horner's syndrome is described.[5] It may present as an autosomal dominant condition or as a spontaneous mutation.

Preganglionic lesions are less common but are more likely to be malignant.

Investigations

CT angiography/carotid ultrasound may demonstrate dissection of the carotid artery.

Pharmacological testing

Pharmacological testing can help to confirm the diagnosis and identify if the lesion is preganglionic or postganglionic:[8]

Cocaine eye drops will normally cause dilatation of the pupil but there is no response in Horner's syndrome. Cocaine inhibits the reuptake of noradrenaline (norepinephrine) but this requires an intact sympathetic system. Cocaine drops can confirm the diagnosis but does not localise the lesion. Their use was universal in the past but has been superseded by the newer agents below.

Apraclonidine is an alternative to cocaine. It has little effect on a normal pupil but causes dilation of a pupil affected by Horner's syndrome.

Hydroxyamfetamine 1% drops can also be instilled to both eyes but it is necessary to wait at least 48 hours after performing the cocaine test. The drops stimulate the release of noradrenaline (norepinephrine) from postganglionic nerves and cause dilation of the pupil (similar to that in the unaffected eye) if these nerves are intact. Hence, a first- or second-order nerve lesion will result in dilation but no dilation occurs with third-order (postganglionic) lesions.

Management

Horner's syndrome is a physical sign. Management involves diagnosis of the underlying condition and treatment as appropriate.

History

Johann Friedrich Horner (1831-1886) was a Swiss ophthalmologist. He was made Professor of Ophthalmology in Zurich in 1873. He described the syndrome that bears his name in 1869.[9] In France it is called Bernard-Horner syndrome, adding the name of Claude Bernard. Horner's other achievements included the observation that red-green colour blindness is transferred to males through the female line.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.